Telegraph system



J. H. BELL,

TELEGRAPH SYSTEM.

APPLICATION mu) NOV. 21. 1917.

. 9 Patented'Dec. 21,1920.

//7 l /7 for. J0/7/7 hf Be/A fly Win/- UNITED srar sg PATENT. OFFICE.

JOHN H. BELLOF sonar; ORANe imw JERsEY, AssIGNoR To WESTERN ELECTRIC COMPANY, INCORPORATED, OF NEW YORK, Y., a CORPORATION OF NEW YORK.

TELEGRAPH SYSTEM.

T 0 all whom it may concern:

Be it known that I, JOHN H. BELL, a citizen of the United States, residing at South Orange, in the county of Essex and State of New Jersey, have invented certain new and useful Improvements in Telegraph Systems, of which the following is a full, clear, concise, and exact description.

This invention relates to telegraph systems, and more particularly to duplex telegraph equipments.

The principal object of this invention'is to provide an improved system whereby the condition of balance on duplexcircuits may be determined or verified in a reliable and eflicient manner. I r I In telegraphic systems wherein service is carried on Over lines equipped for duplex 0peration and in situations where the amount of traflio isimportant and sufficiently heavy to require substantially all of the line time for the transmission operations, it 'will' be readily apparent that any interruption of the line circuit will entail pecuniary loss as well as inconvenience. When multiplex telegraphic working is employed with'such duplexed lines. the capacity and importance of the service is further increased, and additional measures directed to maintaining uninterrupted service on a line are accordingly warranted. I

On duplexed lines, where the electrical condition of the circuit, particularly in the matter of its electrostatic capacity and insulation resistance, are subject to variation, as

commonly experienced on so-called open wire lines, it is important that adjustments be made from time to time in the various parts of the artificial line portion of the equipment in order that a change of insulation on the 'line proper'will not reach a point at which the telegraphic service would actually fail.

The: present system is directed to means for readily verifying the condition of a duplex balance in a manner to meet. the exactions of service as above pointed out, and comprises current indicating 7 means and switching means whereby observations as to balance may be taken in substitution of a single channel or message period ofa plurality of channels or message periods whichcollectivelv occupy the total time of a line circuit. The service features of the system further provide that for an unbalanced con- Specification of LettersPatent.

Patented Dec. 21, 1920.

Application filed November 21,' 1917. Serial No. 203,081.

dition, the indication given will correspond with the relation of the non-balance between a real line and an artificial line and also serve as a measure of the extent of such 11nsuch devices and circuits as will be necessary to a'clear understanding of the invention.

-Referring to the drawing, the reference numeral '1 indicates a telegraph line which is connected serially through'the windings of a polarized relay 2, and an artificial line AL to earth. A developed view of a single channel section or arm A of a sending dis-' tributer comprises a trailer brush 5 which is adapted to traverse a path formedby a collector ring section 6 and five contactor segments 4 adjacent thereto. It will be under-. stood that a suitable telegraph transmitter (not shown), connected to the five segments.

' 41-, controls the combination of current impulses to be transmitted to line. Such combinations may be formed in accordance with the well-known five unit code of Baudot. In traversing its path, the brush 5 successively conne'ctsthe segments 4 with the ring section 6, thereby completing a path .for the transmittercurrents by way of a conductor 7 to the apex or neutral point 8 of the duplexed line 1. From this point a portion of these currents traverse the left-hand winding Of the polar relay 2, and the artificial line AL to earth, while a like portion of current traverses the right-hand winding of the relay 2, and the line circuit 1 to an earth connection at a distant station (not shown).

In addition to these duplex paths a portion of the current from the transmitting equipment alsotraverses a leak circuit extending from the conductor 7 by way of a conductor 9, a relatively high resistance unit 10 and the windings of a polarized switching relay 11 to earth. As well understood in the art, although the utgoing currents'are neutralized and non-effective in the relay 2, they effect the operation of a similar relay at a distant station whereby thecurrent impulses are translated by means to a 'common' or bus conductor 24:. The

seven blades ofthe transfer switch are adapted to be moved together and when in the position shown they establish circuits whereby the condition of balance on the duplex circuits may be ascertained.

V In order that the features of this inven tion may be more readily understood, a description thereof will be further preceded by a" brief description of the operations by which messagesare received from the distant station. Accordingly, let it be assumed thatthe transfer switch 23 is first moved to its right-hand position, whereby the receiver equipment 22 is connected with the receiving section B of the distributer. Incoming impulses from the line 1 traverse the windings ofthe line relay 2, over the circuit already traced, thereby rocking the armature of this relay to engage one or the other of its oppositely positioned contact stops, depending upon the polarity of the incoming impulses. A translating circuit may therefore be traced from a battery 3 bver the armature of the relay 2 by way of a conductor 31, contacts32 of the switch 23, a conductor to the ring section 21,

from which point the circuit is successively establishedby the brush 20 with the receiving segments 2529. The purpose of the five segments 30- will be presently de scribed. From the segments 25--29, the circuits extend through the respectively associated right-hand contacts of the switch 23 to the receiving equipment 22.

It will be understood that an arrangement (not shown) is to be employed for maintaining a synchronous relation between incoming impulses from the line 1 and the arrival of the brush 20 over corresponding ones of the segments 25-29. In response to impulses from the line 1, the relay 2 is therefore operated to selectively establish the battery 3 with the receiving section of the distributer which, in turn, includes such current changes to control the receivingequipment'22, as well understood in the art.

In tracing the various steps in the balance verifying operations,-let it first be as-- sumed thatthe switch 23 is moved to the position in which it is'shown, and that a transfer switch (not shown) at the distant station is also moved to a position to substitute ground connection for a transmitter equipment to five segments of a transmitting distributer arm or section, through which messages are regularly sent to the receiver equipment 22. A branch circuit may now be traced from the linel, over a conductor 34, contacts 35 of the switch 23 and the conductor. 33 to the ring section 21. 7

a second winding 18 of a current indlcator' 16 to a conductor 36, thence over contacts 37 of the switch 23, to the bus conductor 24, common to the five segments 30, and also connected through five respective contacts of the switch 23 with the segments 2529.

The circuits just traced connect the current indicator 16, which may be in the form of a ballistic galvanometer, in series with the brush path of the receiving distributer sec tion B in bridge around the'winding of the line relay 2. The transmitter assumed to be included with the distributer arm A continues the sending of regular. message impulses outwardly over the line 1, and. through the leak circuit, these impulses rock the armature 13 of the relay 11 to one side or the other, depending upon their polarity. At the galvanometer 16 a needle 19 is moved by negative current'through its coil 17 in the same direction that itwould be moved by positive current through its coil 18, and vice versa'. When the duplex equipment is properly balanced, the ohmic resistance, inductance and electrostatic capacity of the artificial line AL is of course equal to the corresponding electrical characteristics of the line 1, as routed through a similar duplex equipment at the distant station. Under such balanced condition, outgoing impulses from the distributer arm 'A will not result in a difference in potential between the external terminals of the relay 2. Therefore, as the brush 20 in its regular lished by the outgoing impulses at the ter minals of the relay 2', and therefore, each time the brush 20 sweeps over the section B, such di'fference'of potential will move the needle 19 of'the galvanometer 16. For convenience ofdescription it may be assumed the connections are such that for a condi tion of unbalance, caused by the'resistance ofthe line 1 being lower than the resist ance of the artificial line, the galvanometer needle will move to the left, and whenthe artificial line is of lower resistance than the line 1, the needle will be deflected to the left, the degree of unbalance being indicated by the range or amplitude of the deflection of the needle.

For the purpose of further illustration,

let it be assumed that the apparent resistance of the line 1 has been diminished, say, through a change from dry to wet weather, and let it be further assumed that a sequence of five alternate positive and negative im pulses are impressed on the segments of the distributer section A, beginning with a negative impulse. Since the brush'20 travels a from left to right, in phase with the brush 5, the first impulse transmitted will move the armature of the leak relayll toits negative position, as shown, at the same in-f stant that the brush 20 completes the relay bridgingcircuit of the galvanometer on the relay 2, by connecting the ring 21'with the segments 25. A portion of the transmitted negative impulse will, therefore, act through the circuit already traced fromthe artificial line side of the relay 2, through the galvanometer coil 17 to the line conductor 1. The next orpositive impulse transmitted from A will bias the. armature of the switching relay 11 to its positive side, whereupon a portion of the transmitted positive impulse will flow from the artificial line side of the relay through the coil 18 of the galvanometer and the brush 20, now at segment 26, t0 the line 1. In acorresponding manner the last three impulses will alternately act through the coils 17 and 18 of the galvanometer, but the needle 19 will be moved in the same direction by each impulse, due to the connected relation of these coils, as already described. Since the direction in which the needle 19 is deflected in the-present example would indicate to anattendant that the resistance of the artificial line was higher than the resistance of the line 1, the" adjustable devices (not shown) of the artificial line may be varied to such point that the needle 19 of the galvanometer 16 willremain atits central or zero position and not be affected by message impulses which continue to be transmitted from A to the line 1.

The period of contact by the brush 5 on each segment at A is substantially equal to the period the brush 20 covers a regular receiving segment, as thesegment 25, at B and an adjacent one of the segments 30, and since all of the segments at B are oined by the switch 23 during the time it is in position for the verifying of balance, circuit at A is completed through'the galvanometer during the full period of each impulse from the transmitting section A.

Since'change to the balance just describedbalance of the duplex circuits, the balance verifying galvanometer may again be switched into circuit and the artificial line v readjusted to a higher resistance to balance that of the line.

From the foregoing description, it will be clear that, for a duplex-multiplex equipped line in which the distributers arev divided into quadrants, each of which are provided with sending and receiving sections, quadruplex service, or four messages in each direction, or eight channel capacity, maybe handled thereover. Since the balancing operations in accordance with the present invention require that only a single channel or one-way one-message time of the line be interrupted, this would be equal to one-eighth of the total message time of such a line. In the same ratio only onetwelfth of the message time of a line would be consumed during the verifying and correcting of duplex balance on a sextuplex or line. 7 7

What is claimed is:

1. In a system of duplex-multiplextelegraphy, a real line, an artificial line, distributer means, a relay connected to form a leak circuit and responsive to currents therein, current indicating means, switching means for rendering a section oft said distributer means ineifective for telegraphing, and circuits jointly controlled by said relay'and said section of the distributer to connect the indicating means for comparing the condition vof electrical balance between said real and artificial line.

2. In a system of duplex telegraphy, a real line, an artificial line, distributer means included with said lines, current indicating means, switching means for connectingsaid current indicating means with said distributer, a relay responsive to message currents in said lines, and means controlled by saidrelay for completing the circuit of said current indicating means whereby the electrical constants of said real and said artificial line may be compared.

3. In a system of duplex telegraphy, a main line, an artificialline,means for trans mitting signals over said main line, means comprising a plurality of controlling cir tive ones of the controlling circuits of said indicating means with said artificial line in cuits for indicating the presence of curorder to determine'whether said main line and artificial line are in electrical balance one with the other. e

4. In a system of'duplex telegraphy, a

real and an artificial line,-means for signaling over said real line, a distributer, means for'indicating thestrength-and direction of currents, switching means for connecting said indicating means'to said real line by way of said distributer, and relay means controlled by telegraphic signals transmit- Y ted to said lines for extending a connec tion from said artificial line to said indicating means to verify the condition of electrical balance of said real line and ficial line onewith another.

5. Ina system of multiplex telegraphy, a real'line, an-artificial line, a plurality of telegraphic equipments, means for signal-' ing over said real line, distr buter means i for successively including said lines with said telegraphic equipments, a relay means responsive to message currents in said lines, a current indicating means, and means for transferring the control of said distributor from a single one of said telegraphic equipments to act cooperatively with sa d relay" means in successively connecting said indicating means to become responsive to'signal- 'ingcurrents in case the real line and arti ficial line are not in electrical balance one with the other. i

6. In a system olduplex telegraphy, real and artificial lines, means for working telegraphic signals over said lines, distributer means for controlling said telegraphic signals, relay means operated by nlessage currents in said l nes, current indicating means, and switching means for rendering said relay means and said distributer means efiective'to establish said indicating means 7 to indicate whether the electrical constants of said real line correspond with the electrical constants of the artificial line.

7. In a system of duplex telegraphy, real and artificiallines, means for working telegraphic signals over said lines,*distributer means for transmitting signals outwardly oversaid real line, distributer means for receiving incoming signals from said real line, a relay responsive to the signals transmitted to said lines, current indicating means, and switching means to transfer the control of said receiving distributer from the reception "of incoming signals to act jointly with said relay in connecting said indicating means between said real and artificial lines to indicate whether said lines are electrically balanced one with another.

8. In a system of duplex telegraphy, a

main line, an artificial line, means for sig naling over said main line, distributor means comprising a plurality of sections for Q respectively controll ng the transmission land reception of signals, means provided said arti-' transmitted impulses thereto with'aplurality of controlling circuits for indicating the strength and direction of cur:

rents, switching means. 'for extending con-.7

n'ections from-said indicating means to said ma nline by way of said d stributer means,

and arelay operated by outgoing message impulses in said lines to control the inclusion of respective ones of the circuitsof said indicating means with said artificial line in phase with changes in the polarity of said transmitted signals for indicating whether said main line is in electrical balance with said artificial line or in which relation they maybe out of balance;

9. In a system of duplex telegraphy, real and artificial lines, several transmitting and several receiving equipments for signaling over said lines, first distributer means for successively including said lines with said telegraph transmitter equipments, second ments,current indicating means, switching means for substituting said current indicating means for one of said telegraph receiv-' ing equipments, relay means controlled by ,distr'ibuter means for successively including said line with said telegraph receiving equip- I transmitted signals to establish said indi- 1 eating means to determine the condition oi balance between said real line and said artificial line, and means controlled by said switching means to render the intervals oi successive contacts on the portionlo'f the distributer controlled thereby to have .a period oi contact equal to the period of successive contacts on said first distributer means.

10. In a system .of duplex telegraphy, a'

real line and an artificial-line, impulse re-' ceivingmeans connected with said'real and artificial line, several telegraph receivers, a receiving distributor for successively inclu0l ing said impulse receiving -means with said telegraph receivers, a plurality of telegraph transmitters, distributer means for successively connecting difi'erent ones of said transmitters with said real and artificial lines at such point thereof as will render I ineffective with said impulse receiving means, relay means responsive to message impulses trans- JOHN H. BELL: 

